The Hepatitis B Clinical Research Network (HB-CRN) is being established to promote "research in hepatitis B focusing upon elucidating the pathogenesis and natural history and developing means of treatment and control". The Network will include up to 10 collaborating Clinical Centers, a Virology Center, an Immunology Center, a NIDDK Project Scientist, and a Data Coordinating Center (DCC). This Network will work cooperatively to create a database of all patients with hepatitis B followed at the Clinical Centers with special focus on newly diagnosed cases. The Network will also include a randomized, controlled trial of long-term mono-versus combination therapy for chronic hepatitis B. Possibly 2-4 clinical trials, clinical or epidemiologic investigations will be conducted by the Network. As the DCC, we will work with the HB-CRN members to support all aspects of study design, study conduct, and data analysis for the database and clinical trials. The DCC will develop a distributed data entry system and maintain a secure, central database of clinical, laboratory, and other relevant information from the Clinical, Virology, and Immunology Centers. The DCC will identify and contract with other central facilities (e.g., laboratory, pathology) as needed and coordinate with the NIDDK Biosample and Genetics Repositories. The DCC will develop safety and efficacy analysis plans and prepare materials for presentations at HB-CRN meetings, scientific conferences, and for publications and regulatory bodies. The DCC will coordinate all activities of the Network, including meetings and conference calls for the Steering Committee, subcommittees, and presentations to the Data and Safety Monitoring Board(s). Finally, we will share data collected for the HB-CRN, participate in translation activities with the wider scientific, clinical, and general community and archive all data, study intervention materials, and coordinate archiving all specimens at the end of the study.